Oops!Anti-ColonialismLast year, researchers excitedly announced that they had found two organic compounds essential for living organisms in samples retrieved from adistant asteroid called Ryugu.The Japanese Space Agency's Hayabusa2 spacecraft obtained the samples from the space rock in 2019 and returned them to Earth in 2020.The discovery reignited an ongoing discussion. What were the conditions necessary for life to flourish on Earth billions of years ago? Did asteroids like Ryugu perhaps seed our planet with life?But now, a team of researchers led by Matthew Genge at Imperial College London has thrown cold water on the hypothesis. As detailed in a recent paper published in the journal Meteoritics & Planetary Science, researchers did find evidence of microbial life while examining the Ryugu samples except that it wasn't from a far-flung asteroid over 100 million miles away.Instead, the microorganisms originated from Earth, indicating that the samples somehow got contaminated by our own pesky microorganisms, underscoring just how hard it is to probe off-Earth samples for evidence of extraterrestrial life."The presence of terrestrial microorganism within a sample of Ryugu underlines that microorganisms are the world's greatest colonizers and adept at circumventing contamination controls," the paper reads. "The presence of microorganisms within space-returned samples, even those subject to stringent contamination controls is, therefore, not necessarily evidence of an extraterrestrial origin."No Place to HideThe microorganisms must've been extremely adept at getting around scientists' best efforts to avoid contamination of any kind.The samples were transported in a hermetically sealed chamber and eventually opened in a nitrogen-purged clean room. Scientists used sterilized tools, themselves stored under nitrogen.Despite their best efforts, the team discovered "rods and filaments of organic matter, which are interpreted as filamentous microorganisms, on a space-returned sample from 162173 Ryugu recovered by the Hayabusa 2 mission," according to the paper.Worse yet, the abundance of these filaments changed over time, highlighting the microorganisms were hard at work colonizing the samples."The discovery emphasizes that terrestrial biota can rapidly colonize extraterrestrial specimens even given contamination control precautions," they concluded, arguing that samples like the ones returned by Hayabusa 2 can easily provide a breeding ground for Earth-based microorganisms.Where that leaves future asteroid return missions remains to be seen;in short, it's one more reason to be skeptical about future claims about the discovery of extraterrestrial life.More on Ryugu samples: Japanese Asteroid Samples Contain the Building Blocks Reveal the Building Blocks for LifeShare This Article